This application is related to applications Ser. No. 648,280, entitled "AIRCRAFT CARGO HANDLING SYSTEM", and Ser. No. 648,201, entitled "CARGO RAIL SYSTEM FOR AN AIRCRAFT", both filed on Jan. 31, 1991.
This invention relates to cargo ramps, and more particularly to a segmented and hinged cargo ramp suitable for moving cargo into and out of the fuselage of an aircraft.
Cargo aircraft today, and more particularly military cargo aircraft, employ a cargo ramp for loading cargo into or unloading cargo from the aircraft cargo bay. Typically, the cargo ramp is of a single piece design which is attached at its forward end to the cargo bed by means of a hinge. During flight operations, it is stowed and latched in such a manner that it serves as the cargo hatch door. For ground operations, the ramp is unlatched and allowed to swing downwardly on its hinge until the end contacts the ground, at which point the ramp is ready for use, bridging the cargo bed and the ground. For loading or unloading vehicles into or out of the cargo bay, a ramp toe is typically used, which allows the vehicles to easily drive onto or off of the ramp.
Most cargo other than actual vehicles is palletized for easier transport, being secured to a standard military pallet. When unloading palletized cargo, the pallets must first be moved down the ramp onto the ground, then reloaded onto ground vehicles such as trucks for transport to their final destination. Forklifts are typically used for reloading the pallets onto the trucks. This is a slow, labor-intensive process, involving much manpower and extensive use of costly and sometimes scarce ground support equipment. This is a particular problem when operations are being conducted on remote austere airfields, where the necessary ground support equipment may be completely unavailable.
The obvious solution to this problem is to place the ramp directly between the aircraft cargo bed and the truck bed, so that the cargo need not be off-loaded onto the ground and then reloaded onto the truck bed, or vice-versa. However, this solution will not work well unless the cargo bed and the truck bed are at the same height. If the truck bed is significantly higher than the aircraft cargo bed, there will be a vertical gap between the end of the ramp and truck bed. If the aircraft cargo bed is significantly higher than the truck bed, the end of the cargo ramp will be sharply angled into the bed of the truck. In either case, transfer of the cargo will be difficult or impossible.
Prior art approaches to this problem have not been particularly successful or desirable. One approach is to employ variable extension landing gear on the aircraft. When loading or unloading is to commence, the landing gear is actuated to raise or lower the aircraft so that the aircraft cargo bed and the truck bed are the same height. Needless to say, variable extension landing gear is very expensive, bulky, heavy, and is also quite slow in operation. Another approach is to standardize truck bed heights and aircraft cargo bed heights. Such an approach is very expensive to implement and necessarily involves design compromises and tradeoffs in either the aircraft or truck designs or both. Furthermore, it would take years to get enough standardized aircraft and trucks in service to make a real difference. What is needed is a simple, compact, inexpensive, and lightweight device which will permit straight-across loading and unloading of cargo onto vehicles which have cargo bed heights different than the cargo bed height of the aircraft.